Shared content and additional platform specific content

For shared content I can have a single mgcb content file of course in a MonoGame Shared Project. If I want additional mgcb content projects per platform what is the way to do it right in Visual Studio 2019? Even though I renamed the individual per platform mgcb files (ContentWindows.mgcb for example) Visual Studio shows me some warnings like this:

Severity    Code    Description    Project    File    Line    Suppression State
Warning        The file '...\Content\Content.mgcb' could not be added to the project.  There is already a link to '...\Content\Content.mgcb'. A project cannot have more than one link to the same file.    MGAndroid 

As I said the content file in the Android project was renamed to ContentAndroid.mgcb and inside the Shared Project there is the default Content.mgcb file? Do I need to do something extra somewhere to fix this? How to do this right?